Dry Fitting Flange......Too Tight...how?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Geo, Oct 7, 2007.

  1. Geo

    Geo New Member

    Messages:
    15
    I am ready to set my toilet flange over the finished floor.

    I am putting a flange on that fits on the outside of the 4" closet bend.

    I want to dry fit it first to make sure it sits on the floor and slides all the way down.

    But it fits really tight and i am afraid it I dry fit it it won't come off.

    Any suggestions? Is there anything that I can put on the pipes to dry fit it that will not hurt the pipes when i decide to glue it. Like some kind of oil or something.

    What do other people do to dry fit aflange and make sure you can get it off afterwards??

    Thanks!!!
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The fit is not just "dry" ; it is what is called an "interference" fit. That means it the fittings deliberatley make tight contact...too tight to go all the way together. This is so when the solvent melts the plastic, there is plenty of material to form the weld joint.

    No amount of lubrication would let them go together. But you can judge the depth of the socket, and when the joint is prepped and solvent applied, it should go together to the full depth of the socket when pressed in place. You can build a little fudge factor into this.
  3. Geo

    Geo New Member

    Messages:
    15
    I can't build any fudge factor into it now as the floor is done and it is concrete.

    My worry is if I apply the glue and slide it on and it does not go all the way down then i am really screwed as the glue will harden and I an digging up the floor at that point.

    I have a spare closet bend like the one in the floor and it fits fine but it is a hassle removing it.

    Are you saying no one would test dry fit this before gluing it?
  4. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    Are you going right into a closet bend or is there some pipe between? I would also check to make sure you measured right. If you are right trying to dry fit it my just cause it to be hard to get back out. I would make sure you check the flange and the fitting you are using. When you have a flange that goes inside a fitting the bottom of the flange just below the ring has a slight bulge did you happen to see this when you were sizing every thing. One simple thing like this could cause all sorts of problems.
  5. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    As already stated, PVC can not be dry fit. I would point out that the pipe does not have to be 100% to the top of the flange. I should be very close, but there is plenty of surface for the solvent weld to make a good joint even the pipe is 1/8" or so short of reaching the top of the flange. You should be able to measure that without too much problem. Be sure the flange is oriented properly when you slip it on the pipe.
  6. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    I agree with you but if the guy has never used pvc before or has the habit of doing it this way. It is a good way to check and recheck things. If he has set his closet bend to high because he took his measurement from the wrong place well... Pointing out things like dry fitting has been mentioned before will not help the guy. Plus I have dry fitted many fittings in the past PCV ABS CPVC Copper ETC... The only time I have a problem is when I use a customers HD fittings.
  7. Verdeboy

    Verdeboy In the Trades

    Messages:
    2,051
    Go ahead and dry fit it. Just don't push it in too hard. Then figure out how much further it will go in (bottom out) when the solvent is used. Try to get it flush with the top of the finished floor, but if you're off by a small bit it will not matter.

    Half the questions on this forum are about flanges that are waaay too high or waaay low, and there's usually a simple remedy for those: flange extenders, extra thick wax, shimming, etc... But yours will be just fine.
  8. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    Dry fitting a pvc flange...difficult?
    You can't dry fit PVC?
    I dry fit 3" + pvc all the time, you have to wiggle it to get it free.
    Also you have to develope a "feel" for how far into the hub the pipe goes, that takes experience.
    For a flange it's easy...push it on then look at the gap (if any) between the pipe and the end of the hub inside the flange.
    Getting it up is simple, use a flat bar and wedge it side to side, once it budges 1/8-1/4" it usually comes off by hand.
    The larger the diameter pipe, the more difficult to dryfit, yes.
    There are situations, like a basement 3"/4" main rough, where dryfitting and using a sharpie is essential on PVC.
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    Measure a few times, look at the flange carefully to make sure it doesn't have a bulge that would prevent it from going down where you want it, then, when you add the solvent, push it down all the way and HOLD it for maybe a minute or so. When you push it on, measure how much further it needs to go, then measure how much room is left in the socket of the fitting. As long as you have a little more room in the socket than you have pipe, it will be able to go down flush onto the floor.

    Because the fitting is tapered, and the solvent lubricated it, it will try to push itself back up...you need to hold it until some of the solvent evaporates and grabs. The bigger the fitting, the longer it takes to evaporate some of the stuff so it will finally lock itself in place. If you just push it down, then let go, it could push itself back up maybe 1/2" over then next minute or so if you aren't holding it down.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,811
    Location:
    Cave Creek, Arizona
    dry fit

    I never dry fit unless it is to prefit and mark some special angle. Whether it will fit or not is why they make rulers. Once we know the measurements are correct, we put the fittings together.
  11. Geo

    Geo New Member

    Messages:
    15
    First off, thanks for all of the help.

    My closet bend is a 4 inch ABS pipe not PVC.

    My flange is also ABS of course.

    One question I have is how much flange pipe needs to cover the closet bend? How much length does ABS need to get a good grip? 1/2"? 1 inch?

    I might cut off the bottom of the flange pipe to the distance I need for a good grip.
  12. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    Swing joints, angles in tight spaces on a house main, dryfit & mark the hubs in place so there's no guessing - on PVC, we don't use ABS much here.
  13. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,347
    Location:
    Cincinnati OH
    We dont use ABS at all.In fact you cant even find it at the supply houses
    in the state.Sch 40 PVC above astm 3034 below grade.
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